BR102013010717B1 - ELECTRIC POINT WELDING HEAD FOR AN INDUSTRIAL MULTI-AXIS ROBOT, AND ROBOT UNDERSTANDING THIS HEAD - Google Patents

Abstract

electric spot welding head for a multi-axis industrial robot, and robot comprising this head. an electric spot welding head for a multi-axis industrial robot having a compact configuration, particularly in a longitudinal direction extending from the head end to affixing to the robot pulse towards the welding electrodes (101,102). This result is primarily achieved by the fact that the head-mounted electrical transform (t) has its output poles (118, 119) connected to the electrode holder arms (103, 104) arranged respectively in a front wall (121). said transformer body (t) and an end wall (124) of said transformer body for connection to the electrode holder arms (103,104) of the head. the welding head structure is completely covered by a housing (105) having a rear opening for connection to the robot pulse (20) and a front opening from which the welding head electrode arms (103, 104) design

Description

(54) Title: ELECTRIC POINT WELDING HEAD FOR A MULTI-AXIS INDUSTRIAL ROBOT, AND ROBOT UNDERSTANDING THIS HEAD (51) Int.CI .: B23K 11/11; B23K 11/31; B23K 11/36 (30) Unionist Priority: 5/15/2012 EP 12168084.7 (73) Holder (s): COMAU S.P.A.

(72) Inventor (s): FULVIO FERRERO; ENRICO MAULETTI (85) National Phase Start Date: 04/30/2013

1/13 “ELECTRIC POINT WELDING HEAD FOR A MULTI-AXIS INDUSTRIAL ROBOT, AND ROBOT UNDERSTANDING THIS HEAD”

The present invention relates to the field of spot welding heads for multi-axis industrial robots, of the type comprising:

- a support structure with an end portion for attachment to the robot wrist,

- a pair of welding electrodes supported by respective electrode holder arms mounted on said support structure,

- at least one of said electrode holder arms is movably mounted on the head support structure between an open position and an open position,

- an actuator for the operation of said movable arm mounted on said support structure, and

- an electrical transformer for applying the electric welding voltage to the welding electrodes, having a box with a rear wall facing said rear end portion for attachment to the robot wrist, a front wall opposite the rear wall, two side walls parallel to a general plane defined by the two electrode holder arms and two end walls, said transformer further comprising an electrical connector for connecting the current distribution cable of the welding head, and two output poles of said transformer, electrically connected to the two electrode holder arms.

The aim of the invention is to make a welding head that has compact dimensions, particularly in the longitudinal direction that goes from the end of the head arranged for attachment to the robot pulse in the direction towards the welding electrodes.

Another objective of the invention is the realization of a head that guarantees protection of the cables and / or tubes associated with the head against the risk of interference with foreign bodies during the use of robots in a production installation, and especially the risk of deterioration. premature cables and / or tubes due to exposure to aggressive external agents (welding splashes, dirt, etc.) that are present in an industrial production line. This deterioration implies, in fact, in the known devices, frequent replacements (up to once every one or two years) of the trim, with consequent stops and low productivity of the robot.

In order to achieve these objectives, the invention refers to a welding head having the characteristics specified above and further characterized by the fact that the two output poles of said transformer, electrically connected to the two electrode holder arms, are arranged as such: a on the front wall and the other on an end wall of said box transformer.

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Thanks to this provision, the connecting strips connecting the outlet poles of the electrical transformer to the respective electrode arms can be arranged in configurations that guarantee a more compact size of the welding head, particularly in the longitudinal direction of the head, that is, in a direction from the end of the head arranged for attachment to the robot pulse in the direction to the welding electrodes.

According to another preferred feature, the structure of the welding head is completely covered by a box formed by two side covers of plastic material, coupled together, having main walls parallel to the general plane of the two electrode holder arms, said box having a rear opening for the connection of the welding head support structure to a flange supported by the robot pulse and a front opening, from which the two electrode holder arms of the welding head protrude.

The head of the invention is preferably used in a robot of the type comprising a base structure, an articulated robot pulse and a chain of mutually articulated robot elements that connect said base structure to said robot pulse, wherein said pulse robot end additionally ends with a flange to which a tool is rigidly connected, which requires a supply of energy and / or a supply of fluid, and where through said chain of mutually articulated robot elements and through said robot pulse a internal continuous passage is defined, in which one or more cables and / or tubes for said power supply and / or said fluid supply for the tool are received.

A robot of the type specified above is, for example, described and illustrated in the US document. 8,006,586 B2 held by the same Depositor.

In robots of the type specified above, the cable and pipe lining for the energy supply and the fluid supply for the welding head, supported by the robot, pose several problems. On the one hand, it is necessary to prepare retention and guide systems for these cables and tubes, which minimize the risk that they may interfere or become entangled with foreign bodies when using robots on a production line. On the other hand, it is also necessary to guide these cables or tubes in order to reduce the flexion and torsion deformation as much as possible, to which they are subjected during the movements of the robot, and especially in order to reduce the deterioration, to which the cables they are subject to exposure to aggressive external agents (welding spatter, dirt, etc.) that are often found on industrial production lines. Exposure of cables to these agents often leads to greater and premature wear of such components, with the result that the cable and tube packing must be replaced more frequently (even after only one or two years since first use),

3/13 consequently requiring a greater number of stops and lower productivity of the robot. Finally, it is also important to prepare the trim in such a way that its replacement can be carried out in a simple and quick manner.

According to another aspect, the present invention also relates to a multi-axis industrial robot including a compact welding head according to the invention and further characterized by the fact that said cables and / or tubes for the supply of energy and / or the fluid supply to the welding head continues without interruption in a passage formed through said robot flange to the head, whereby said cables and / or tubes are arranged completely inside the robot and inside the head, without the need to provide separate cables or tubes for the head connected to the robot cables and tubes in correspondence to said flange, as occurs, in contrast, in the known solutions.

Therefore, in this specific preferred embodiment, the welding head according to the invention is provided with electrical connectors and fluid connectors for direct connection of supply cables and tubes belonging to the robot, and is therefore devoid of its own cables and / or tubes, intended to be connected to the robot's cables and / or tubes.

An essential advantage of this solution is that the total protection of the supply cables and tubes completely avoids the premature wear of these components, determined in the known solutions, from contamination by aggressive external agents (welding splashes, dirt, etc.) present in the environment industrial. Experiments conducted by the depositor have allowed us to predict that the invention will result in a huge advantage in terms of fewer robot pad replacements, given that the average duration of a pad can vary from a minimum of about 1.5-2 years to a minimum. minimum time of about 8-10 years of age, almost comparable to the life of the robot. The invention is, therefore, capable of producing a real advance in the practice of using robots.

Of course, the compact welding head according to the invention can also be used in a robot of the traditional type.

In addition, the robot described above, with cables and / or internal tubes for the robot, which continue without interruption until the welding head mounted on the robot, could also be used with a conventional welding head, or by any other type of tool , and for this reason, this robot also forms the subject of a copending patent application by the same Depositor.

It should also be noted that, for reasons of easier maintenance, the tubes to supply fluid to the tool can also be provided with a separate end portion, associated with the tool and connected by means of quick couplings to the corresponding tubes associated with the robot. . In this case, the basic principle

4/13 of the invention is also applied to the electrical cables (power and / or signal) associated with the robot.

The invention will now be described with reference to the accompanying drawings, provided purely by way of non-limiting example, in which:

- Figure 1 is a perspective view of a first embodiment of the welding head according to the present invention,

- Figure 2 is a schematic side view of the internal structure of the welding head in Figure 1,

- Figure 3 is a perspective view of the internal structure of the head of Figure 1,

- Figure 4 is a perspective view of the electrical transformer arranged in the welding head in Figure 1,

- Figures 5-8 are viewed in perspective on an enlarged scale that illustrate various details of the internal structure shown in Figure 2,

- Figure 9 is a perspective view of a second embodiment of the welding head according to the invention,

- Figure 10 is a schematic side view of the internal structure of the welding head in Figure 9,

- Figure 11 is a perspective view of the internal structure of the welding head in Figure 9,

- Figure 12 is a schematic representation of a multi-axis industrial robot according to the prior art from the depositor's document US 8.006.586 B2, reported here purely as an example of a robot, in which the welding head of the invention is to be applied,

- Figure 13 is an enlarged scale and sectional view of the robot pulse in Figure 12,

- Figure 14 is a schematic side elevation view of a first modality of robots according to the invention,

- Figure 15 is a schematic perspective view of a second modality of the robot of the invention,

- Figure 16 is a perspective view of the robot in Figure 14, with the welding head removed,

- Figure 17 is another schematic side view, partially sectioned, of the robot in Figure 3, and

- Figure 18 is a perspective view on an enlarged scale of the connection support between the robot flange and the support structure of the welding head.

Figure 1 shows a perspective view of a first embodiment of the welding head according to the invention. The number 100 indicates the

5/13 welding as a whole, comprising two welding electrodes 101, 102 supported by respective electrode holder arms 103, 104. The internal structure of the head is hidden by a box 105, having a rear opening for connection to the robot pulse and a front opening from which the electrode arms 103, 104 of the welding head protrude. The box 105 is formed by two side half-covers 105a, 105b coupled together, having main walls parallel to the general plane defined by the two electrode holder arms 103, 104 and locked by the locking rods 106. Figure 1 also shows the wall rear 107 of a connection flange 108, best seen in Figure 18, which serves to connect the flange F of the robot pulse to the support structure of the welding head. As shown in Figure 18, support 108 includes rear wall 107 and two wings 109 that are parallel and spaced, projecting orthogonally from rear wall 107.

With reference to Figures 2, 3, the welding head 100 comprises a support structure 110, including two steel plates 111 that are parallel and spaced, rigidly connected to each other and parallel to the general plane defined by the two electrode holder arms 103, 104, that are mounted between the two plates. The structure of the electrode holder arm 104 is rigidly connected by screws to a pair of supports 112 (Figure 3) attached to the internal surfaces of the two plates 111. The structure of the electrode holder arm 103 is, in contrast, connected to an oscillating arm 113 which is articulated mounted between the two plates 111 around an oscillation axis 114 and which is controlled by the rod 115 of an electromechanical actuator 116, this also being mounted between the two plates 111.0 actuator 116 is properly of a known type, comprising a electric motor, a gearbox and a nut set in rotation by the electric motor via the gear unit. The rotation of the nut causes a linear movement of a threaded screw inside it, this screw being connected to stem 115. The components of actuator 116 are not illustrated here, because, as stated, this actuator can be made according to any known configuration and the elimination of these details from the drawings makes the latter more immediately and easily understood.

The electric welding current is supported through electrodes 101, 102 by passing it through the structure of the arms 103, 104, made of aluminum, and having a hollow prism configuration, with side walls showing lighting holes 117. The arm body 103, 104 is electrically connected to the two output poles 118, 119 of an electrical transformer T arranged between the two plates 111 of the welding head support structure.

Also with reference to Figure 4, the body of said transformer T has a rear wall 120 facing towards the robot flange, a front wall 121 opposite it, two side walls 122, and end walls 123 and 124 (upper and lower). bottom,

6/13 respectively, in the orientation shown).

In accordance with a fundamental characteristic of the invention, which makes it possible to provide the particular compactness for the welding head, the two output poles 118 and 119 of said transformer T are arranged on different walls of the body of said transformer. In the example shown, pole 118 is provided on the front wall 121, while pole 119 is provided on the lower end wall 124. Poles 118, 119 are also electrically connected to the structure of the respective arms 103, 104 by means of an elastic band deformable 125, having a general U-shaped configuration (Figure 2) and a strip 126, also elastically deformable, having a general S-shaped configuration. The arrangement of one of the two output poles of said transformer T (specifically the pole 119) on the lower wall 124 of said transformer T allows the reduction of the distance in the horizontal direction of Figure 2 between said transformer T and the electrode holder arms 103, 104. Consequently, the size of the head results in being particularly reduced in its longitudinal direction, that is, in a direction that goes from the robot flange in the direction to the welding electrodes 101, 102.

Both said transformer T and welding electrodes 101, 102 require fluid cooling. Therefore, in the bundle of cables and tubes that come from the robot at least one refrigerant supply pipe and at least one refrigerant return pipe are included. With reference to Figures 4, 5 and 6, the refrigerant supply tube sends the refrigerant fluid over the entire refrigeration circuit (not shown) provided within said transformer T. from the internal refrigeration circuit to said transformer T , the refrigerant fluid flows through two channels 127a, 127b, formed respectively in the cylindrical bodies that constitute the outlet poles 118, 119 of said transformer T. The duct 127a projects radially from the body 118, while the duct 127b protrudes coaxially, at the end of the terminal body 119. At the outlet end of the ducts 127a, 127b, connectors (not shown) are arranged for the connection of the tubes that conduct the refrigerant fluid to the arm 103 and the electrode 101 and to the arm 104 and electrode 102, respectively. In particular (see Figure 2), electrode 101 then receives the refrigerant through a flexible tube 128 arranged through the internal cavity of the arm 103, the refrigerant heated by electrode 101 then being transported into another flexible tube 129, this is also arranged in the internal cavity of the arm 103. The proximal ends of the tubes 128, 129 are connected via connectors 130 (see Figures 2 and 7). One of the two connectors 130 is connected by a flexible tube to the connector arranged at the outlet end of the duct 127a (Figure 5), while the other connector 130 is connected to the flexible tube (not shown) that returns into the robot, without passing through of said transformer T. This duct transports the refrigerant return fluid from electrode 101 to the robot.

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Additionally, inside the arm 104, two flexible tubes 131, 132 are provided to send the refrigerant fluid to the electrode 102 and to return the refrigerant fluid that cooled the electrode 102. The two flexible tubes are indicated with 131, 132 and are connected to two connectors 133 (Figures 2 and 8). One of the two connectors 133 is connected via a flexible tube (not shown) to the connector arranged on the outlet end of the duct 127b (Figure 6), while the other connector 133 is connected to the flexible tube which is returned directly into the robot.

Figure 4 of the attached drawings also shows that on the rear wall 120 of said transformer T, a three-pole electrical connector D1 is provided, for the connection of electric power cables, with the three poles aligned in a direction parallel to the transverse direction of the head ( that is, the direction orthogonal to the general plane of the two arms). On wall 120 a D2 electrical connector for electrical signal cables is also arranged. Such connectors are intended to receive cables that come directly from the robot, in the case of the application where the head is integrated into the robot and is not provided with its own cables and / or tubes. However, as already indicated, the head according to the invention can also be used in any robot of the known and conventional type, in which the head can be quickly connected to the robot pulse and is provided with its supply cables and tubes that are connected to the cables and tubes belonging to the robot.

Figure 9 of the accompanying drawings is a perspective view illustrating a variation of Figure 1 that corresponds to the version with the sliding arm of the welding head. In this Figure, the parts common to those in Figure 1 are designated by the same reference numbers. Also in this case, the structure of the welding head 100 is completely covered by a box 105 consisting of two half-covers 105a, 105b joined together by the tie connection means at 106. The support structure of the welding head of Figure 9 is visible in Figures 10, 11. It is essentially analogous to that of the version already described above, except that in this case the fixed arm 104 has an elbow configuration in such a way that the electrode 102 is arranged on the axis of the actuator 116. The other arm 103 consists of a slide rod guided within a prismatic guide 200 supported at the ends by two plates 201 attached to plates 111 of the head structure. The rod 103 is connected at its end to the rod of the actuator 116 so as to be linearly displaceable along the axis of the actuator 116 between an open position, where the electrodes 101, 102 are spaced, and an open position, where these electrodes are in contact with each other. The arrangement of said transformer T is identical to that described above with the outlet poles of said transformer T arranged on the front wall and on the bottom wall of said transformer. In this case, the elastically deformable strip 125 has a horizontally oriented U-shaped configuration (Figure 10), instead of vertically, as in the case of the version of Figure 2

8/13 and is directly connected to the rod that constitutes the arm 103. Also in this case, a cooling circuit for the electrodes is evidently provided, similar to the one described above with reference to Figure 2, which is not shown in Figure 10 for further simplification of the drawing.

As mentioned repeatedly, the welding head according to the invention can be used in any robot of known type. Merely as an example, Figure 12 shows the robot known from US 8.006.586 B2.

In the case of the example shown in Figure 12, the robot 10 comprises a base structure 12 that supports a rotating upright 13 around a first vertical axis I. The upright 13 in turn supports a vertical arm 14 rotating around a second axis II, directed horizontally. The upper end of the vertical arm 14 in turn supports a structure 16 which supports an arm 18, rotatable about a third axis III, horizontally directed. The arm 18 is supported by the structure 16 around a fourth axis IV, which coincides with the main axis of the arm 18. The distal end of the arm 18 supports an articulated wrist 20 which is illustrated in an enlarged scale and in section in Figure 13 As will be apparent in the following section, the main feature of pulse 20 is the fact that it is a hollow pulse, adapted to define a continuous passage within itself, where the bundle of supply cables and tool tubes can be guided. It is evident, however, that the teachings of the present invention are also applicable to a robot having any different configuration and in particular a hollow pulse of a configuration different from that illustrated here by way of example.

With reference to Figure 13, the pulse 20 comprises a first hollow body essentially in the form of an elbow 22, and including a first and a second end and a passage cavity, leading to these ends. The first end of the first hollow body 22 is intended to be rigidly connected by means of screws 19 to the rotating robot arm 18 around the IV axis. The pulse 20 further comprises a second hollow body essentially in the form of an elbow 24, and comprising a first and a second end and a passage cavity leading to those ends. The first end of the second hollow body 24 is mounted on the second end of the first hollow body 22, rotatable about an axis V inclined with respect to the first axis IV. The pulse 20 finally comprises a third hollow body 26 comprising a first and a second end and a passage cavity leading to those ends. The first end of the third hollow body is mounted on the second end of the second hollow body 24, rotatable about an axis VI inclined with respect to the second axis V.

As already indicated, the passage cavities of said first, second and third hollow bodies 22, 24, 26 form a continuous passage along axes IV, V, VI,

9/13 through which cables and / or tubes for the supply of energy / fluid are arranged as well as the control of the tool associated with an F flange supported by the third hollow body 26. Said passage has a substantial capacity, whereby the number The total number of cables and / or tubes it can receive is considerable.

For example, in the case where the tool is an electric spot welding head, the power supply lines that pass through the internal passage of the robot pulse comprise two refrigerant supply tubes, two fluid return tubes refrigerant, a cable for the control signal of an electrically driven motor from the cylinder head, a current distribution cable for this electric motor, a cable for multiple bus bars, and three power supply cables (or, alternatively, a single power cord with three metallic wires) for the electric welding current.

Again with reference to the illustrated example, the axes IV and VI are inclined with respect to the V axis by an angle between about 50 ° and 70 °. Preferably, this angle of inclination is 60 °. This choice of inclination of the axis of rotation V, in relation to the axes IV and VI, allows to obtain an extensive working range of the robot pulse, and at the same time guarantees a simple and continuous passage of the cables and / or tubes inside of the wrist. As can be seen, in the condition that the axes IV, V, VI are coplanar, they define a configuration of Z,

Again with reference to the illustrated example, at the connection between the arm 18 and the hollow body 22, a housing for a first group of gear motors 27 is provided. According to the size of the first hollow body 22 and its cylindrical portion intended to be coupled to the robot arm 18, the housing for the first gear motor 27 can be entirely contained in the first hollow body 22 or even partially in the arm 18 of the robot, but always in such a way that the first gear motor 27 is essentially included within the volumes defined by the geometry of the arm 18 and the first hollow body 22, with particular reference to the volume of the section of this arm. In correspondence with the second hollow body 24, another housing for a second gear motor 29 is provided. In particular, as shown in Figure 13, the hollow body 24 has an external seat on its side wall, on which the second gear motor 29 is received, essentially oriented parallel to the VI axis. Thanks to the elbow conformation of the hollow bodies 22 and 24, the gear motor 29 is found spaced from the walls of the hollow body 22 in order to never interfere with the latter whatever the angular position assumed by the hollow body 24 with respect to the hollow body 22. The triangular arrangement of the gear motor 29, described above, allows the maintenance of the transverse volume of the pulse within a limited limit. Also, since the gear motor 29 is tilted with respect to the V axis by an angle equal to the

10/13 angle of inclination of the VI axis with respect to the V axis, in this case equal to about 60 ° when it is put in rotation by the hollow body 24, the inertia forces that oppose the rotation movement of the gear motor 29 are limited.

Between the first hollow body 22 and the second hollow body 24, a single cross roller bearing 33 of a known type is arranged, having an inner ring 32 and rigidly connected to the first hollow body 22, while an outer ring 34 is rigidly connected to the second hollow body 24. A single cross roller bearing 37 is also provided between the second hollow body 24 and the third hollow body 26, with an outer ring 36 rigidly connected to the second hollow body 24 and an inner ring 38 rigidly connected to the third body hollow 26.

Each gear motor 27, 29 comprises a motor 28, 30, a coupling flange 31, a gear box 40, as already indicated above, and a pinion 42, 46. Gear boxes 40 are characterized by a high gear ratio transmission and are preferably of the epicyclic or harmonic type. Each gearbox 40 is coupled at one end to its relative motor 28, 30 via coupling flange 31. The coupling flange is connected by screws 35a to motor 28, 30 and the gearbox via other screws 35b.

At the other end, gearbox 40 supports pinion 42, 46 for the transmission of movement, which is now fixed by means of a plurality of screws 35c. The first gear motor 27 comprising the first motor 28, gear box 40 and a tapered pinion 42 is fixed by screws in contact with a wall 39 of the base of the respective housing. Between the wall 39 of the housing base and the end of the gearbox, to which the tapered pinion 42 is attached, a flange 41 for fixing and adjusting the clearance is interposed. During the assembly of the pulse, the thickness of the bushing 41 is adapted in order to obtain the correct gearing of the pair of bevel gears. The taper pinion 42 meshes with the internal teeth of a ring bevel gear 44, and this, being fixed by means of screws (not shown) to the outer ring 34 of the bearing 33, is rigidly connected to the second hollow body 24. The second motor gearbox 29 comprising the second motor 30, gearbox 40 and a cylindrical pinion 46 is inserted into the housing formed in the second hollow body 24 and is fixed in contact with a wall 43 of the base of said housing by means of screws. The cylindrical pinion 46 engages with a cylindrical ring wheel 48 which is fixed to the inner ring 38 of the bearing 37. The rotation movement from the motor 28 is transformed through the gearbox 40 and transferred to the conical pinion 42 which rotates the ring bevel gear 44 rigidly connected to the outer ring 34 of the bearing 33, in turn attached to the second hollow body 24. In this way, the rotation of the second hollow body 24 about the V axis is supported. When the second motor 30 is activated, the

11/13 rotation is transferred through gearbox 40 to cylindrical pinion 46. The cylindrical pinion 46 engages with the wheel cylinder 48, which is rigidly connected to the inner ring 38 and the third hollow body 26. In this way, the rotation of the third hollow body 26 about the VI axis is supported.

The internal cavity of the wrist allows the passage of supply cables and / or C ducts from the welding head, intended to be associated with flange F. These cables and / or C ducts are associated with a bushing 47.

A possible application of the welding head according to the invention provides the assembly of the head of a robot of the known type, illustrated in Figures 12, 13 described above. According to the prior art, this assembly is carried out with the help of a quick fixing system and provides a connection between supply cables and tubes belonging to the robot and cables and tubes belonging to the head.

Another particularly advantageous application is that which provides a complete integration of the welding head according to the invention in a robot of the type specified above, with the elimination of cables and tubes from the head and direct connection of cables and tubes from the robot to the connections provided on the head. Such integration could also be carried out with a welding head different from that forming the material of the present invention or by any other type of tool, and for this reason it also forms the subject of a copending patent application from the same Depositor.

Figure 14 of the attached drawings shows a first variant of this solution of a robot with an integrated head. In this Figure, the parts common to those in Figure 12 are designated by the same reference number.

Figure 14 shows a modality in which the welding head of Figure 1 is integrated in the robot, in which one of the two electrode holder arms is fixed, while the other arm is oscillatingly mounted. Instead of such a welding head with a swing arm, it is possible, however, to provide a welding head of the type shown in Figure 9, in which one of the two electrode holder arms is fixed and the other arm is linearly slidable, as specifically shown in Figure 17.

As seen in Figure 17, the robot shown and the robot known from Figure 12 have in common the fact that, through the entire chain of robot elements and through the robot pulse, a continuous internal passage is defined, in which the beam C of supply cables and tubes is received. In Figure 17, the case where all of the cables and tubes are contained within a single flexible housing is illustrated, but this feature is evidently not essential and the bundle of cables and tubes can simply be provided along its length of a plurality clamping clamps.

In the case of known robots, and also in the specific case of the known robot illustrated in Figures 12, 13, the bundle of supply cables and tubes is interrupted in

12/13 corresponding to the connection flange F of the tool associated with the robot. Typically, such a flange is provided with a plurality of connections for connecting cables and tubes arranged in the robot with separate cables and / or tubes that are associated with the welding head mounted on the robot.

In contrast to this arrangement, in the robot in Figures 14-17, the quick replacement of the welding head supported by the robot is not provided, and the welding head is not provided with separate cables and tubes that are connected to cables and tubes of the robot when the head is mounted on the robot flange. As clearly visible in Figures 16, 17, in the case of the robot shown in these Figures, the cables and tubes that pass through the entire extension of the robot and the hollow robot pulse continue without interruption in a passage formed through the F F1 flange (Figure 16 ) to an input connector provided on the electrical transformer T arranged within the structure of the welding head.

As will be apparent from the description that follows, the invention therefore provides a single bundle of cables that runs through the entire robot, the robot pulse and reaches the user equipment on board the tool, in such a way that the extension The entire bundle of cables and tubes is completely contained within the robot structure, within the pulse structure and within the welding head structure.

therefore, in the case of the specific application, illustrated in Figures 14-17, the welding head is completely integrated within the robot, so that the robot and the welding head together form a single welding machine, without any distinction between the robot part and tool part and without any possibility of quick tool replacement. This solution, compared to the solution known from US 8.006.586 B2, has the advantage of not providing any connector for the connection between robot cables and tubes and separate cables and tubes arranged on board the welding head and therefore , does not cause the disadvantage of this known solution, in which the cables and tubes associated with the head, which extend from the robot flange towards the head, are at least partially exposed to the outside.

As we have seen, this advantage is further enhanced by the provision of the outer box 105 for the welding head, which forms an extension of the robot body and which completely hides the cable and pipe section extending beyond the robot flange.

Figure 15 shows another application of the invention, in which robot 10 has a structure essentially identical to that of the robot in Figure 14, but is mounted in the inverted position, with the base structure 12 attached to a ceiling 13 (an overhead frame) of an industrial installation.

Figure 16 shows the robot in Figure 14 with the welding head disassembled and

13/13 highlights, as in the robot according to the invention, the bundle of cables and tubes C that exit through a central opening F1 of the robot flange F and continue directly to connectors R that connect directly to the electrical connectors and the couplings hydraulic elements provided inside the welding head. The beam C thus extends from the base of the robot to the equipment inside the welding head, remaining completely hidden inside the robot structure and inside the box 105 of the welding head 100 without any exposed part, even in the final section between the F flange of the robot and the equipment inside the welding head, and without any interruption or connection of cables or tubes on the robot flange. This provision is also clearly visible, as already described above, in Figure 17, which refers, as an example, to the case of a welding head of the sliding electrode type; it being understood that it is also immediately applicable to the case of a welding head with swing arm.

Of course, without prejudice to the principle of the invention, the details of construction and the modalities can vary widely with respect to what is described and illustrated purely by way of example, without departing from the scope of the present invention.

In particular, as repeatedly highlighted, the welding head according to the invention can be used in any type of robot, the applications illustrated here being provided only as a preferred example.

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Claims (7)

1. Electric spot welding head for a multi-axis industrial robot, comprising: - a support structure (110) with an end portion for attaching to the robot wrist (20), - a pair of welding electrodes (101, 102) supported by respective electrode holder arms (103, 104) mounted on said support structure (110), - in which at least one of said electrode holder arms (103) is movably mounted on the support structure (110) of the head (100) between an open position and an open position, - an actuator (116) for driving said movable arm (103) mounted on said support structure (110), and - an electrical transformer (T) for the application of the electrical welding voltage to the welding electrodes (101, 102), having a housing with a rear wall (121) facing in the direction towards said rear end part of affixing to the wrist. robot, a front wall (120) opposite the rear wall, two side walls (122) parallel to a general plane of the electrode holder arms (103, 104) and two end walls (123, 124), said transformer further comprising an electrical connector (D1) for the connection of the current distribution cable of the welding head, and two output poles (118, 119) of said transformer (T), electrically connected to the two electrode holder arms (103, 104), said welding head being characterized by the fact that the two output poles (118, 119) of said transformer (T), electrically connected to the two electrode holder arms (103, 104), are arranged in different walls of said transformer (T ) box, p referentially one on the front wall (121) and the other on an end wall (124). 2. Welding head according to claim 1, characterized in that the structure of the welding head is completely covered by a box (105) consisting of two side half-covers, made of plastic (105a, 105b), coupled together, having main walls parallel to the general plane of the two electrode holder arms, said box having a rear opening for the connection of the welding head support structure (100) to a flange (F) supported by the robot pulse and a front opening , from which the two electrode holder arms (103, 104) of the welding head (100) protrude. Welding head according to claim 1 or 2, characterized in that the support structure (110) of the welding head comprises two support plates (111) parallel to each other and spaced apart, rigidly connected with each other and parallel 2/2 to the general plane of the two electrode holder arms (103, 104), said electrode holder arms, said transformer (T) and said actuator being mounted between said support plates (111). 4. Welding head according to claim 3, characterized by the fact that said support plates (111) are fixed to the rear of a support (108) for affixing to the flange (F) supported by the robot wrist, having a U-shaped configuration, with two wings (109) attached respectively to the two support plates (111) and a rear wall 107) for affixing to said flange (F). 5. Welding head according to any of the preceding claims, characterized by the fact that said head is provided with electrical connectors (D1, D2) and fluid connectors for direct connection of supply cables and supply tubes belonging to the robot , and is therefore devoid of cables and / or its own tubes intended to be connected to the robot's cables and / or tubes. 6. Welding head according to any of the preceding claims, characterized by the fact that said outlet poles (118, 119) of the electric transformer (T) have cylindrical bodies with internal passages for a refrigerant fluid, connected to the cooling circuit. cooling of the welding electrodes (101, 102). 7. Multi-axis industrial robot, comprising: - a basic structure (12), - an articulated robot pulse (20), and - a chain of mutually articulated robot elements (13, 14, 16, 18) connecting said base structure (12) to said robot pulse (20), - wherein said robot pulse (20) ends with a flange (F) for attaching an electric spot welding head (100), which requires an energy supply and / or a fluid supply, - in which, through said chain of mutually articulated robot elements of (12, 13, 14, 16, 18) and through said robot pulse (20), a continuous internal passage is defined, in which one or more cables and / or tubes for said power supply and / or said fluid supply for the tool (100) are received, characterized by the fact that said robot comprises a welding head according to claim 1 and in which the said cables and / or tubes (C) continue without interruption in a passage (F1) formed through said flange (F) and up to said welding head (100), whereby said cables and / or tubes are arranged completely inside of the robot and inside the welding head, without the need to lay separate cables or tubes for the head (100), connected to the cables and tubes of the robot in correspondence to said flange (F). 1/14